Stop in for a cup of coffee

It was never common knowledge to Americans, either -- except for a few Americans in the vehicle lighting industry. :)



1940: the first standardised sealed-beam headlamp, a 7-inch round unit, 6 volts, 40/30 watts (high/low), called the 4030.

1950 or so: wattage is increased to 50/40 (high/low) and the new lamp is called the 5040.

1956: aiming pads (three little protrusions in a triangular formation on the front of the perimeter of the lens) and a filament shield (to block stray light that causes backdazzle in bad weather) are added. Wattage stays the same at 50/40. 6v unit still called 5040, new 12v unit called 5400

1958: The reflector focus is improved. Wattage stays the same at 50/40. There is now an effort at a standard system of nomenclature: the first digit indicates the size, the next digit indicates the service application (0 for headlamp), the next digit indicates the revision/version, and the final digit specifies the subtype (high/low beam headlamps, known as "type 2", have a 2 as the final digit; high-beam "type 1" headlamps have a 1).

For whatever reason, the first digit for 7-inch headlamps is "6", while the first digit for the new 5.75-inch headlamp is "4". (the other major market where sealed beam headlamps are used, the British Commonwealth, uses "7" for the first digit of 7" lamps and "5" for the 5.75" lamps). So in the American system, the new 5.75" lamps are 4002 for the 37.5/50w high/low beam (4005 for the heavy-duty version), and 4001 for the 37.5w high beam. The 6v 7-inch unit is now called 6006, and the 12-volt unit is called 6012.


This system of nomenclature breaks down very quickly as the industry seems to make and break rules at random:

1970: the 7" headlamp is upgraded to 60/50w and is now designated 6014. Heavy-duty or long-life versions by various makers are 6015 or 6016. The 5.75" high/low beam headlamp is upgraded to 37.5/60w and is now designated 4000. A heavy-duty, vibration-resistant/long-life version of the 4000 is called the 4040.

1975: the small rectangular (165 × 100mm) four-headlamp system comes along. The 40/60w high/low beam is 4652 and the 50w high beam is 4651 ("46" makes sense because those metric dimensions are more or less 4" × 6", but now we're using the first two digits for the size…)

1977: the big rectangular (200 × 142mm) two-headlamp system comes along. The 65/55w lamp is called 6052 (now we're using "6" for something other than a 7" round lamp, and a random "5" to differentiate from the "1" in 6012, but even though we've got about the same filament wattage as the 6014 lamp, we're using "2" as the final digit…).

1977 or so: GE buys a couple million 60/55w H4 halogen bulb burners (just the glass capsule with filaments inside) from two European makers and begins making halogen sealed beams: H6014 7" round and H6052 200 × 142mm rectangular. Wagner follows suit around 1980, only they call their rectangular unit H6050 (just whatever, pick any digit; they're all good).

1979: US regs change to allow double the high beam intensity. New 5.75" round high beam is a 50w item called 5001. Halogen version is H5001. Halogen small rectangular 50w high beam is H4651.

1984: US auto industry wants lower-wattage headlamps so they can use cheaper switches and wiring. US lighting industry devises a homegrown 35w halogen capsule. Poorer-but-still-legal performance. Now we've got the H6024 (7-inch round halogen 35w high/low beam…except Philips calls theirs H6017), the H5006 (5.75" round 35w high/low beam), the H4656 (small rectangular 35w high/low beam), and the H6054 (large rectangular 35w high/low beam).

1987: Truck-duty extra-long-life halogen sealed beams: H5024 7" round, H5054 large rectangular, H5062 and H5051 small rectangular, and H5501 and H5506 (or H5009) small round—now we've decided the first digit doesn't mean anything and the rest of them are pretty much random.

1992: higher-performance sealed beams with what used to be the standard wattages (65/55 or 60/55 high/low), but we keep the designations adopted for the low-wattage lamps and just add whatever suffix each individual maker likes. GE calls their "High Output" lamps H6024HO, H6054HO, and H4656HO. Sylvania calls theirs H6024XV, H6054XV, and H4656XV. Wagner calls theirs H6024BL, H6054BL, and H4656BL.

So now there's pretty much nothing left resembling any kind of standard numbering system.

Notes:
1. Years are approximate in this longer answer than you probably wanted, and it doesn't go into some of the little-known but really cool sealed beams made in places like Japan, the UK, and the Netherlands.

2. I sometimes wonder what it's like to think of car lights in terms no more complicated than present/absent, works/doesn't, on/off, bright/dim, and white/red/amber.
Dan - Great summary. Occassionally you or someone on CPF have dropped a bit of chronology, but I don't recall seeing a relatively complete summary anywhere.
beer-gif-gif.gif

That Carina would have had sealed beams in its home Japanese market, but European-type headlamps were put in cars exported to countries where that type was either required or most commonly used. That's an R2 bulb you've linked. Tungsten non-halogen, 45/40w high/low beam in 6- and 12-volt versions; 55/50w in the 24-volt version used in European trucks and buses. It was almost 100% universal in European headlamps (that is, headlamps built to comply with the European regs, no matter who built them or where) starting in 1957. This bulb came in white and selective yellow.

When the Brits and Europeans devised the world's first halogen 2-filament (high/low beam) headlight bulb, the H4, in the late 1960s, they kept the filament geometry compatible with that of the R2, so it was an easy matter to make hybrid bulbs: an H4 burner on an R2 base. Thus were old headlamps updated to halogen technology just by changing the bulb.

Do you know what lamps and bulbs Scott Harvey was refering to in the 1967 Sportscar Graphics rally prep and tips article? Could it be H4 that early?
"Several makes of European headlights have a very flat top cut-off on both beams. These lights are as good in snow or fog as any fog light I have used. Also, they have a relatively low current-draw, so their bulbs have quite a long life. They are not sealed beam, so they continue to function even if the lens is cracked. These headlights double as good fog-lights..."
Scott Harvey Sports Car Graphic (May 1967) page 70.


What you refer to as "selective yellow" we used to call "fog lights". :)

Bill
Bill, I see Dan already answer but for future reference --- Whenever you see some text in blue font and underlined, that's a link to more info. Some of us - especially SlantsixDan - frequently include links in this manner. You can roll over with a mouse and your browser will show the URL in case you like to know where link is going. (I sure do!)

Clearing out and closing down the 3-generation family home my grandparents put up 70 years ago. The developer's bulldozers come for it in 20 days. It is a death in the family, an uphill slog of sadness, grief, and trauma.

You asked.
Sorry to hear. Always tough losing things with memories. We learn to let go because we have no choice. A part of life I suppose - at least for most.